Effects of strain rate and temperature on deformation behaviour of IN 718 during high temperature deformation

Hot Forging of IN718 with Solution-Treated and Delta-Containing Initial Microstructures

“…1 using both peak and steady-state stresses, are presented in Table 3. An activation energy of 430 kJ mol -1 for hot-working of solutiontreated IN718 (Type I microstructure) is in good agreement with values derived for the same material in the literature, 390-440 kJ mol -1 [8][9][10][11]. Higher values of Q for the Type II and Type III materials, as listed in Table 2, can be attributed to the presence of d precipitates; second-phase particles are known to affect the measured hot-working activation energy in steels [22] and two-phase titanium alloys [23].…”

“…2a, b. The overall behavior is in broad agreement with that usually observed for IN718: A distinct peak stress, tending to be more pronounced at higher strain rates, is followed by significant post-peak flow softening that is generally attributed to recrystallization and/or adiabatic heating [6][7][8][9][10]. Since all the flow curves presented here have been corrected for the effect of deformation heating, the observed flow softening must, in this case, be due to the evolving microstructural state of the material.…”

“…Significant research has been directed toward characterizing the precipitation and dissolution kinetics of the d phase in IN718 during heat treatment and aging, e.g., [1][2][3][4][5], and several experimental investigations have explored recrystallization associated with high-temperature compressive flow in solution-treated material, e.g., [6][7][8][9][10], but there has been rather less focus on the specific role of d precipitates during hot deformation. However, it is known that prior aging in the d stability field can have a significant effect on stress-strain response [11,12] and recent studies have highlighted the complexity of the mechanisms involved, including dynamic dissolution and reprecipitation [13], sub-grain formation [14], and platelet spheroidization [15].…”

The Deformability and Microstructural Aspects of Recrystallization Process in Hot-Deformed Fe-Ni Superalloy

“…The behaviour of metals and alloys during hot plastic working has a complex nature and it varies with the changing of such process parameters as (Zhou et al, 1994): deformation, strain rate and temperature. The high-temperature plastic deformation is coupled with dynamic recovery and recrystallization processes which influencing the structure and properties of alloys.…”

Modelling Microstructural Transformations of Nickel Base Superalloy in 718 During Hot Deformation

“…[1][2][3][4][5][6][7][8][9][10][11][12]), they either fall into the category of being too simplistic and producing only an average grain size and approximate volume fraction recrystallised, or are far too complicated and too computationaly intensive to be used on a daily basis by process engineers. A model is required, therefore, that can be run within a commercially available finite element package, or in tandem with one, that will deliver detailed results, run in a reasonable time, and be simple to use.…”